Question

The Intelligence Quotient (IQ) test scores for adults are normally distributed with a population mean of 100 and a population standard deviation of 25. What is the probability we could select a sample of 25 adults and find the mean of the sample is more than 110?

Answer 1

Solution :

Given that,

mean = =  100

standard deviation = =25

n=25

= = 100

= / n = 25 / 25 = 5

P( >110 ) = 1 - P( < 110)

= 1 - P[( - ) / < ( 110-100) / 5]

= 1 - P(z < 2)

Using z table

= 1 - 0.9772

= 0.0228

probability= 0.0228